This disclosure is directed toward power machines. More particularly, this disclosure is related to control of engine throttle in power machines. Power machines, for the purposes of this disclosure, include any type of machine that generates power for accomplishing a particular task or a variety of tasks. One type of power machine is a work vehicle. Work vehicles are generally self-propelled vehicles that have a work device, such as a lift arm (although some work vehicles can have other work devices) that can be manipulated to perform a work function. Work vehicles include loaders, excavators, utility vehicles, tractors, and trenchers, to name a few examples. While the following discussion is provided in the context of loader type power machines and work vehicles, the discussion is not intended to be limited to loaders.
Operators of loaders, including skid steer loaders and track loaders, are required to control different machine functions simultaneously, using hand and/or foot controls. Machine functions which must typically be controlled include forward and reverse travel, turning/steering, travel speed, lift arm actuation (lift) through actuation of a lift cylinder, bucket or implement orientation (tilt) through actuation of a lift cylinder, and auxiliary functions such as those associated with an attached implement. For example, using a joystick control pattern referred to as an “ISO pattern”, the right-hand joystick controls lift functions (fore-aft movement of the joystick) and tilt functions (side-to-side movement of joystick), and the left-hand joystick controls forward and reverse travel and turning. Using an alternative joystick control pattern referred to as an “H pattern”, the left joystick is used to control the left-side drive functions (forward and reverse movement and speed of left side tractive elements) and lift functions, while the right joystick is used to control the right-side drive functions (forward and reverse movement and speed of right side tractive elements), tilt functions, and auxiliary hydraulic functions. Other patterns can be used.
While controlling the above-discussed functions with a pair of joystick controls, an operator of some types of loaders must typically use a foot pedal or other user input device to control an engine operating speed, referred to more simply as “engine speed”, using the foot pedal to vary the speed of the engine as may be advantageous during the operation of the loader. Such foot pedals are often biased to a minimum engine speed setting, requiring the operator to engage the foot pedal to provide more than a minimum amount of engine speed. That is, these types of foot pedals are momentarily activated devices. Alternatively or in addition, a baseline throttle input that can be set to any engine speed setting in the engine's operation range can be employed to adjust the minimum amount (or simply set the engine speed when no momentary input such as the foot pedal discussed above is available). Because these inputs are manually controlled, even a skilled operator may command more or less throttle speed than is optimal, resulting in increased fuel usage or inadequate power delivery.
To ensure that the engine is operating at a high enough engine speed, referred to as rotations per minute (RPM), to sufficiently power the hydraulic systems to perform the above-mentioned work functions, it is common for an operator to use a baseline throttle input to set the engine speed to a high RPM level, and to leave the engine at this level while performing various tasks requiring user input device manipulation to control forward and reverse travel, travel speed, turning, lift arm function, tilt function, and auxiliary functions. Since the high RPM level is not typically required at all times while performing these functions, this practice results in the use of more fuel than is required, creates more wear on the engine than is required, and creates more noise than is required. In the alternative, if the operator uses the throttle input to set the engine speed to a low RPM level, the machine may be underpowered when attempting to perform these functions, resulting in poor performance, engine stalls, and the like.
The discussion above is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter.